Originally posted by solarisdreams How far from the wall should I take my test shots? Should I zoom full-in, full-out? Apperature ISO settings?
Thanks,
Victor
All of the above. I did my tests at 16, 20, 28, 35, and 50mm, at 2.8, 4.0, and 8.0, and at three different distances. Text-filled newspaper taped VERY FLAT to the wall can do it too. You want to take the first set as close to minimum focus distance as you can, and try to make each successive set at least a foot away. Use ISO100. Use a tripod. Use the 2-second timer to avoid mirror vibration.
As Poke pointed out, compare the center to the corners and edges. The corners will always be softer, especially at 2.8, but you should be able to tell if it is abnormally soft. Look for doubling, which my lens had at 28mm, but not at the extremes. Post pics with full-res crops of the center and corners if you're unsure.
Will